Al/F codoping effect on the structural, electrical, and optical properties of ZnO films grown via atomic layer deposition

Aluminum/fluorine-codoped zinc oxide (AFZO) thin films were prepared on silicon and glass substrates through atomic layer deposition at 150 degrees C. Their structural, electrical, and optical properties were investigated as functions of the F/Al codoping ratio. The X-ray diffraction analysis revealed that the preferred growth orientation changed depending on the codoping with F, that is, from (0002) for Al-doped ZnO (AZO) films to (1010) for the AFZO ones. The electrical resistivity of the AFZO films (around 5.0 x 10(-4) Omega.cm) was lower than that of the AZO ones; this was mainly attributed to an increase in the n-type carrier concentration (from 4.11 x 10(20) cm(3) for AZO to 5.86 x 10(20) cm(3) for AFZO) due to the substitution of the Zn and O sublattice sites by, respectively, the Al and F atoms. The enhanced carrier concentration affected also the optical property of the AFZO films according to the Moss-Burstein shift. The carrier mobility was similarly improved (from 6.96 cm(2)/V.s for AZO to 21.2 cm(2)/V.s for AFZO) by the passivation of the oxygen vacancies via the F-doping.

Automated summary

AFZO thin films were prepared through atomic layer deposition with improved electrical and optical properties compared to AZO films, attributed to increased carrier concentration and mobility via codoping with F and Al.